Drive for refrigeration systems or the like



Dec. 15, 1959 M. M. HANN 2,91

DRIVE FOR REFRIGERATION SYSTEMS OR THE LIKE Filed Sept. 28, 1956 545cmMOTOR ENG/NE z? 19 CONOE/V6'0R ENS/NE INVENTOR.

MW 772 HW 5y BYXM f?"'""" United States Patent DRIVE FOR REFRIGERATIONSYSTEMS OR THE LIKE Melvin M. Hann, Rockford, Ill., assignor toSundstrand Corporation, a corporation of Illinois Application September28, 1956, Serial No. 612,766

1 Claim. (Cl. 6053) This invention relates to drives for refrigerationsystems or the like and to controls for such drives.

It is a general object of the invention to provide a new and improveddrive of the character described and to provide new and improvedcontrols therefor.

A more specific object is to provide a new and improved drive forrefrigeration systems or the like including a hydraulic pump forsupplying fluid under pressure to drive one or more of a plurality ofhydraulic motors, and auxiliary means for driving one of the pluralityof hydraulic motors mechanically when the pump is inoperative so thatthe motor functions as a pump for supplying fluid under pressure todrive the other of the hydraulic motors.

It is also an object of the present invention to provide, in a drive forrefrigeration systems of tractor-trailer units wherein the pump isdriven by the tractor engine, new and improved controls including meansresponsive to a pump load condition for controlling the tractor engineidle speed so as to maintain thev idle speed when a load is imposed onthe engine to thereby avoid stalling the engine.

Other objects and advantages will become readily apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

Fig. l is a diagrammatic showing of a refrigeration drive and controltherefor embodying the principles of the present invention;

Fig. 2 is a diagrammatic showing of a fragmentary portion of the driveillustrated in Fig. 1, showing certain of the parts in a secondposition;

Fig. 3 is a diagrammatic showing of a fragmentary portion of the driveillustrated in Fig. 1, showing a modification of a control for thedrive; and

Fig. 4 is a diagrammatic showing of the drive and control illustrated inFig. 3, showing certain of the parts in a second position.

While illustrative embodiments of the invention are shown in thedrawings and will be described in detail herein, the invention issusceptible of embodiment in many different forms and it should beunderstood that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiments illustrated. The scope of theinvention will be pointed out in the appended claim.

This invention constitutes an improvement over the drive of my copendingapplication, filed September 19, 1955, as application Serial No.535,146.

The drive of the present invention is particularly adapted forrefrigeration systems of tractor-trailer units or the like. Such systemsmay be comprised of a number of separate or combined componentsincluding a compressor 10, a condenser 11 having fans 12 and 13, and aremotely located evaporator 14 having a fan 15.

Drives of the character described may advantageously be driven normallyfrom the prime mover for the tractor, such as the engine 17, and asillustrated, include a ice hydraulic motor 18 for driving the condenserfans 12 and 13 and for driving the compressor 10, and a hydraulic motor19 for driving the evaporator fan 15. The condenser fan 12 is secured onthe shaft 20 of the hydraulic motor 18, and the shaft 20 is providedwith a pulley 21 connected by a belt 22 to a pulley 23 on the shaft ofthe compressor 10 to drive the compressor. The condenser fan 13 issecured to the shaft of the compressor.

When the tractor engine is not in operation, which may occur under anumber of conditions, the compressor, and condenser and evaporator fans,may be driven by means of an auxiliary A.C. electric motor 25 having onits drive shaft a pulley 26 connected by belt 27 to a pulley 28 on theshaft 20 of the hydraulic motor 18, all as described more in detailhereinafter.

Normally, however, motors 18 and 19 are driven by means of fluid underpressure supplied from a hydraulic pump 29 connected to be .driven bythe tractor engine 17. Fluid is supplied to the hydraulic pump 29 from areservoir 30 connected by a line 31 to the pump intake. The pumpdischarge is connected by a line 32 to the inlet for the hydraulic motor18. The outlet from hydraulic motor 18 is connected by a line 33 to theinlet for the hydraulic motor 19. The pump discharge and the hydraulicmotors 18 and 19 are thereby connected in series. The outlet fromhydraulic motor 19 is connected with a conduit 34 for returning fluid tothe reservoir 30. Leakage fluid from the casing of the pump 29 and fromthe casing of the hydraulic motor 18 may be conducted in a conventionalmanner through leakage lines (not shown) leading to the reservoir 30.

With the system as described thus far, it will be seen.

that on operation of the tractor engine 17, the pump 29 will thereby bedriven to supply fluid under pressure for driving the hydraulic motors18 and 19, with return fluid from the motor 19 being conducted to thereservoir 30. The condenser fans 12 and 13, the compressor 10 and theevaporator fan 15 are thereby driven to operate the entire refrigerationsystem. During operation of the hydraulic motor 18, when its shaft 20,the pulley 28, the belt 27, and the pulley 26, are all driven, theelectric motor 25 free wheels.

Obviously, the speed of the tractor engine 17 may vary during itsoperation, and variations in speed of the engine are effective to varythe displacement of the pump 29. If desired, the pump may includecontrols of the character described in my copending application referredto above to provide a constant supply of fluid to the hydraulic motor 18and the hydraulic motor 19 in order that these motors will be operatedat a constant speed. Additionally, if desired, the pump 29 may beprovided with a solenoid controlled valve generally designated 39, ofthe character described in my aforesaid copending application, forfeathering or disabling the pump 29 so thateven though the tractorengine and pump are driven, no fluid is delivered for operating themotors 18 and 19. In this manner the refrigeration equipment includingthe condenser fans, the compressor, and the evaporator fans may bedisabled during the operation of the tractor engine 17. The hydraulicpump 29 and the hydraulic motor 19 may, if desired, be of a constructiondescribed more in detail in my aforesaid copending application.

Under some conditions, it may be desirable to operate the evaporator fan15 separately, that is, without operating the condenser fans 12 and 13or the compressor 10.

valve 41 may be opened so that fluid under pressure delivered to theline 32 passes through the conduit 40 and to the conduit 33. Fluid underthe same pressure is thereby delivered to both the inlet and the outletfor the motor 18 and the motor is thus not operated. However, fluidunder pressure flows to the inlet for the motor 19 and this motor isoperative to drive the evaporator fan 15.

As previously indicated, it may be desirable to operate therefrigeration system at a time when the tractor-engine is not operating.Such an event may occur, for example, when the tractor-trailer unit isat a standstill or garaged for an overnight period. It is for thispurpose that the electric motor 25 is provided. The motor 25 may besupplied with power through leads such as those illustrated at 44 froman outlet convenient to the place where the tractor-trailer is garaged.

As previously described, when the hydraulic motor 18 is driven by fluidunder pressure from the pump 29, the motor 25 free wheels. However, whenthe motor 25 is driven, the hydraulic motor 18 does not free wheel.Instead, the motor 18 may be of a conventional construction such that itfunctions as a pump when driven by the electric motor 25. In this case,the condenser fans 12 and 13 and the compressor are driven by theelectric motor 25. Also, the hydraulic motor 18 functions as a pump,drawing fluid in through the conduit 32 and supplying fluid underpressure to drive the hydraulic motor 19.

During operation as described immediately above, it is undesirable thatfluid be drawn through the pump 29 to the hydraulic motor 18 which isthen functioning as a pump. Accordingly, the hydraulic system includes aconduit 46 connected with the conduit 31 leading from the reservoir tothe pump 29 and also connected with the conduit 32 leading to thehydraulic motor 18. The conduit 46 is provided with a blocking valve47Which may be normally closed to prevent flow of fluid through theconduit 46. Upon energization of the electric motor 25, the valve 47 maybe opened to bypass the pump 29 and to connect the reservoir 30 directlyto the inlet to the motor 18.

The blocking valves 41 and 47 may, if desired, be of the constructiondescribed in detail in the copending joint application of myself andHarry C. Moon, Jr., filed December 30, 1955, as Serial No. 556,540. Asdescribed in the joint application referred to, such valves may besolenoid operated, and are thus conveniently adapted for use in thehydraulic circuits described herein.

When the tractor-trailer unit is in operation, and the load of therefrigeration drive described may thereby be imposed on the tractorengine, but at a time when the tractor engine is idling, the load of therefrigeration drive may be sufiicient to stall the tractor engine.Obviously, this is an undesirable condition. Accordingly, the presentinvention encompasses the provision of control means to prevent stallingthe engine by maintaining the engine idle speed when a load is imposedon the hydraulic pump 29. The function of such control means is tomaintain the engine idle speed substantially constant, regardless of theload imposed thereon by the pump 29. For example, if the engine normallyidles at about 500 r.p.m. when no load is imposed, it is desired thatthis speed be maintained when a load is imposed.

Referring to Fig. l, the tractor engine is provided with carburetionapparatus generally designated 50 including a carburetor having a supplyline 51 and adapted to control the supply of fuel to the truck enginethrough a line 52 so as to control the speed of the engine. Mechanicallinkage is provided for controlling the carburetor and includes anelongated rod 53 suitably connected with a foot operable pedal 54. Aspring 55 is provided to bias the carburetor linkage and the foot pedal54 toward a normal position determined by adjustable stop screw 55' atwhich the engine 17 idles normally when no load is imposed thereon bythe pump 29. In order to avoid stalling the engine 17 when a load isimposed on the pump 29, the rod 53 associated with the carburetorlinkage is provided with an abutment member 56 engageable with a movablymounted stop 57 which is controlled in response to the dischargepressure from pump 29.

As illustrated in Figs. 1 and 2, the stop 57 comprises a piston rodconnected with a piston 58 reciprocable in a cylinder 59. A spring 60acts against one end of the cylinder and against one side of the pistonto normally bias the stop 57 to a position which permits return of thecarburetor linkage to its normal idle position. The opposite end of thecylinder 59 is connected by a conduit 32a to a line 32 which deliversthe high pressure pump discharge. In this manner, when the pump 29 isdelivering at a high pressure discharge and a load is thus imposed onthe tractor engine 17, the pressure of fluid in the conduits 32 and 32awill be sufiicient to move the piston 58 and stop 57, against the biasof the spring 60, to a position which prevents return movement of thecarburetor linkage to a normal engine idle position and instead limitsmovement of the carburetor linkage under the urge of spring 55 to anidle position with power sufiicient to maintain operation of the tractorengine 17 at a speed such that the engine will not be stalled by theload imposed thereon. Movement of the piston 58 and stop 57 in a poweridle direction may be limited by a stop sleeve 59 fixed in the cylinder59 and engageable by the piston 58. Fig. 1 illustrates the stop 57 andthe carburetor linkage in the so-called power engine idle position,while Fig. 2 illustrates these parts in a normal idle position.

Referring now to Figs. 3 and 4, l have illustrated a modification of acontrol for preventing stalling of the engine 17 when idling and when aload may be imposed thereon by the pump 29. As seen in these figures,the control includes a stop 61 which constitutes the rod of a piston 61'normally biased by a spring 62 to a position wherein the stop 61 engagesabutment member 56 to maintain the carburetor linkage in a power idleposition. Movement of the stop 61 in power idle direction may be limitedby a stop sleeve 62 fixed in the cylinder which houses the piston 61'.The stop 61 comprises the core of a solenoid having a winding 63 which,when energized, is effective to move the stop to a position which freesthe carburetor linkage for return movement under the urge of spring 55to a normal engine idle position defined by stop screw 55.

The solenoid valve 39 for feathering or disabling the pump 29 includes awinding 64 which when energized is elfective to feather the pump. Thewinding 64 is connected to ground at 65 and is connected by means of awire 66 to a source of power such as a battery 67, which may, ifdesired, be the tractor battery normally provided for purposes such asstarting. A normally open switch 68 connected in circuit with thewinding 64 and with the battery 67 may be closed to effect energizationof the winding 64 and thereby disable the pump. The switch 68 may be acontrol switch of the character described in my aforesaid copending soleapplication. For example, the switch may be associated with the door tothe refrigeration compartment in a manner such that the switch is closedwhen the door is opened, or the switch may be a thermostaticallycontrolled switch which is closed when the refrigeration compartment isno longer in need of refrigeration. Alternatively, the switch 68 may bemanually operable, if desired.

The winding 63 for effecting movement of the stop 6. to a slow idleposition is connected by a wire 69 in circuit with the switch 68 andwith the battery 67 so that when the pump is feathered the stop 61 issimultaneously moved to the normal engine idle position. In this manner,it will be seen that the carburetor linkage is maintained in a poweridle position during such. time as the pump is not feathered or disabledand thus during such time as a load may be imposed on the engine by thepump, but when the pump is disabled or feathered, the carburetor linkagemay return to a normal idle position. Fig. 3 illustrates the parts in apower idle position, and Fig. 4 illustrates the parts in a normal idleposition.

I claim:

A drive for refrigeration systems including a compressor apparatus andan evaporator apparatus comprising, first and second hydraulic motorsadapted for connection respectively with the compressor apparatus andthe evaporator apparatus of said refrigeration system for driving thesame, a hydraulic pump for supplying fluid under pressure to drive thehydraulic motors, a reservoir, a supply conduit connecting the reservoirand the pump inlet for supplying fluid to the pump, a first pressureconduit connecting the pump outlet and the first motor inlet, a secondpressure conduit connecting the first motor outlet and the second motorinlet, whereby the pump and the first and second hydraulic motors areconnected in series with each other, a return conduit connecting theoutlet from the second hydraulic motor to the reservoir, a first bypassconduit connected to said first pressure conduit and said secondpressure conduit in parallel with the first motor, valve means in saidfirst bypass conduit normally closed to block fluid flow therethroughand openable for bypassing the first hydraulic motor and connecting thepump discharge directly to the second hydraulic motor to drive thelatter separately, an electric motor mechanically connected to the firstof the hydraulic motors and to said compressor apparatus, said electricmotor being operable to drive the first hydraulic motor and thecompressor apparatus when the pump is inoperative thereby to cause thefirst motor to pump fluid under pressure to drive the second hydraulicmotor, a second bypass conduit connected to said supply conduit and tosaid first pressure conduit in parallel with the pump, and valve meansin saidsecond bypass conduit normally closed to block flow therethroughand openable when the pump is inoperative and said electric motor isemployed to drive the first hydraulic motor, to bypass the pump andconnect the first hydraulic motor intake directly with the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS2,077,974 Wishart Apr. 20, 1933 2,104,696 Hanson Jan. 4, 1938 2,112,466Maloon Mar. 29, 1938 2,264,821 Zukoski Dec. 2, 1941 2,518,316 Henny Aug.8, 1950 2,530,241 Harrington Nov. 14, 1950 2,562,367 Robinson July 31,1951 2,618,932 Taup Nov. 25, 1952 2,628,470 Orton Feb. 17, 19532,741,895 Horvath Apr. 17, 1956 2,746,240 Brown et al May 22, 19562,753,696 Guerra et a1. July 10, 1956

